Re: [PATCH v2 2/4] dt-bindings: gnss: add mediatek binding

[Loys Ollivier]

On Fri 25 Jan 2019 at 09:07, Johan Hovold wrote:

> On Thu, Jan 17, 2019 at 05:54:32PM +0100, Loys Ollivier wrote:
> > Add binding for Mediatek-based GNSS receivers.
> >
> > Signed-off-by: Loys Ollivier <lollivier@xxxxxxxxxxxx>
> > ---
> >
> > v2:
> > Renamed bindings from Globaltop/gtop to Mediatek/mtk.
> > Moved current-speed as an optional propertie.
> > Removed the status line in the example.
> > Added "mediatek,mt3339" compatible.
> >
> >  .../devicetree/bindings/gnss/mediatek.txt          | 39 
> >  ++++++++++++++++++++++
> >  1 file changed, 39 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/gnss/mediatek.txt
> >
> > diff --git a/Documentation/devicetree/bindings/gnss/mediatek.txt 
> > b/Documentation/devicetree/bindings/gnss/mediatek.txt
> > new file mode 100644
> > index 000000000000..fd984b4a9a6d
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/gnss/mediatek.txt
> > @@ -0,0 +1,39 @@
> > +Mediatek-based GNSS Receiver DT binding
> > +
> > +Mediatek chipsets are used in GNSS-receiver modules produced by several
> > +vendors and can use UART, SPI or I2C interfaces.
> > +
> > +Please see Documentation/devicetree/bindings/gnss/gnss.txt for generic
> > +properties.
> > +
> > +Required properties:
> > +
> > +- compatible	: Must be one of
> > +
> > +			"globaltop,pa6h"
> > +			"mediatek,mt3339"
>
> I'm not sure it makes sense to add the GPS chip itself as it cannot be
> used stand-alone AFAIU, and either not way would require a lot more
> resources to be defined than what you add to this binding.

OK, I find it a bit confusing to have Mediatek bindings but no
compatible Mediatek SoCs.
But it is true that it can't be used stand-alone. I will remove this
reference and also remove it from the mtk.c driver code from this patch
serie.

> > +
> > +- vcc-supply	: Main voltage regulator (pin name: 3V3_IN, VCC, VDD)
>
> The pin names in parenthesis were copied from the sirf-star binding and
> were used to capture the various names given to this supply by different
> vendors. Please drop as it doesn't apply here.
>
> > +
> > +Required properties (I2C):
> > +- reg		: I2C slave address
> > +
> > +Required properties (SPI):
> > +- reg		: SPI chip select address
>
> While the mt3339 appears to support these interfaces, the globaltop one
> does not.
>
> Have you looked around for a small sample of mt3339-based receivers, to
> see whether anyone actually provides these?

Again I'm confused by the fact that it is the Mediatek bindings.
Hence why I have added it and why it was not present in the v1 that was
only for Globaltop.
I find it odd mentionning the chipset but not all its interfaces.
I will remove these sections and only list supported interfaces (i.e.
UART). Other interfaces can be added afterward if one finds a board that
provides them.

> > +Optional properties:
> > +
> > +- timepulse-gpios	: Time pulse GPIO
> > +- v-bckp-supply		: Backup voltage regulator
> > +- current-speed		: Default UART baud rate
>
> Looks like you forgot the optional NRESET input and 3D-FIX output (even
> if the latter might be of limited use).

Thanks I will clean this section.

> > +
> > +Example:
> > +
> > +serial@1234 {
> > +	compatible = "ns16550a";
> > +
> > +	gnss {
> > +		compatible = "globaltop,pa6h";
> > +		vcc-supply = <&vcc_3v3>;
> > +	};
> > +};
>
> Johan


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-L